Winnipeg Forecast

Tuesday, 31 December 2013

#7 - The 4 major snowstorms & blizzards of early 2013

The first 3 months of 2013 featured 4 major snowstorms and blizzards. Coincidentally, all but one occurred on a Monday!

A Colorado Low January 11-12 brought the first blizzard in the RRV since March 2011. Winds of 50-60 km/h and gusts over 70 km/h combined with abundant fresh snow. 10-15 cm fell in Winnipeg while 15-25 cm fell to the southeast, including about 20 cm in Steinbach. Roadways were extremely trecherous, visibilities were near-zero for several hours and snow drifts approached a metre deep in some areas. Visibility at Winnipeg airport was 1 km or less for 27 consecutive hours.

A vigorous Alberta Clipper brought another blizzard to the RRV February 17-18. The storm began as freezing rain and ice pellets in the afternoon of Feb 17, covering highways southeast of Winnipeg in ice. Blizzard conditions by evening lasted until the following afternoon. Conditions were worst south of Winnipeg where winds of 60-70 km/h gusted up to 80 km/h. Whiteout conditions prompted the closure of highways 1, 16, 59 and 75. In total, 4-7 cm of new snow fell in Winnipeg while 10-15 cm fell to the south and east. The storm caused power outages in Windsor Park, St. James and in the town of Île-des-Chênes. In addition, a 54-year old man passed away west of Landmark after leaving his vehicle stranded in the ditch during the blizzard.

Another vigorous Alberta Clipper moved in March 4. Heavy snow bands hovered south and southwest of Winnipeg for hours dumping 30-60 cm of snow. Upsloping along the escarpment due to strong east winds enhanced totals. Some totals included 56 cm in Miami, 35 cm in Morris, 20-30 cm in Brandon and 12-19 cm in Winnipeg (click here for a totals map). 5 cm fell in 1 hour in Winnipeg, highlighting the snow's intensity. The storm was blamed for knocking out power to about 5,500 residents in Linden Woods.

A Montana Low March 17-18 gave the RRV its third blizzard of the winter. The worst conditions were south of Winnipeg where winds of 50-60 km/h gusted to 70 km/h. Generally, 10-17 cm of snow fell across southern Manitoba. Whiteout conditions prompted the closure of highway 75, as well as Fermor Avenue east of Lagimodière Boulevard in Winnipeg. Visibility was so bad that snow plow operations were halted in the Morris area. After the storm, snow depth sat around 50-80 cm across southern Manitoba. A depth of 58 cm in Winnipeg was the deepest in March since 1966.

#6 - A week of drenching thunderstorms

The June 20 to 26 period was the highlight of flash flooding this year in southern Manitoba.

Storm south of Wpg before it entered the city

On June 20, a quasi-stationary t-storm cell over southwest Winnipeg dumped 50-75 mm of rain over a very isolated portion of the city in about 2 hours. Rainfall amounts dropped off very quickly as you moved away from the storm. A few kilometres away only a few millimetres fell, including a measly 8.5 mm in south St Vital and 1 mm in northeast Winnipeg. This steep gradient looks impressive on the City of Winnipeg's rainfall map seen here. Flash flooding made some roads almost impassable and many properties experienced flooding, including the newly built Ikea which was evacuated. A Weather Moment blog has a great summary of the event.

Two rounds of widespread thunderstorms early June 22 and 23 in southwestern Manitoba dumped biblical rainfall. In total, both events dumped 80-150 mm of rain from Melita to Brandon to Dauphin, creating severe overland flooding. The town of Reston was hit hard with over 140 mm of rain. Floodwaters were so deep that part of the town had to be evacuated. Winnipegosis and Pipestone were also hard hit. In Brandon, 90-120 mm of rain caused street and basement flooding.

Also on June 22, a line of very slow moving storm cells northwest and southwest of Portage la Prairie in the afternoon and evening dumped unimaginable rainfall. Radar estimates pointed to 150 + mm of rain in just a few hours northwest of Portage.

Lastly, severe thunderstorms June 25 dumped more heavy rains in southwestern Manitoba. Unfortunately, Reston was once again hit hard, receiving 104 mm of rain! Storms in the area then merged into a squall line which raced through the RRV at night. Frequent lightning, strong winds and torrential rains occurred. As much as 30 mm fell in southern parts of Winnipeg. A home was struck by lightning in northeast Winnipeg, igniting a fire, but no one was injured. In addition, winds up to 100 km/h caused power outages in southwestern Manitoba.

Radar imagery from the NWS of the squall line as it began racing across southern Manitoba

#5 - January in November

Winter began with a fury this year with frequent blasts of unseasonably cold air in late November. The cold conditions were especially prevelent in the last 10 days of the month when temperatures dropped well into the minus teens and twenties at night. At times daytime highs were in the minus teens, some 10 degrees below normal.

Most impressive was on November 23 as a very strong arctic high pressure system moved into southern Manitoba. With a morning low of -26.8°C at Winnipeg airport, it was the coldest November night since November 26, 1996 when we dipped to -27.9°C. Temperatures were much colder out west, dipping to the -30's in Saskatchewan and parts of western Manitoba.

However, the biggest story was the high pressure. Winnipeg reached its highest pressure reading ever recorded in November since these records began in 1953. Standardized sea-level pressure topped out at 104.86 kPa (or station-level pressure of 101.64 kPa). This beat the previous station level pressure record of 101.53 kPa on November 20, 1978.

Top 7 highest station-level pressure readings in November in Winnipeg since 1953

#10 - A return to reality; a colder and very snowy winter

The second half of January and the first few days of February featured the coldest weather in 2 years. 8 days saw temperatures dip below -30°C, the first -30°C readings since February 2011. A low of -33.1°C on January 20 ended a 694-day streak without reaching -30°C, the second longeststreak of its kind since 1872. The longest was a 714 day-streak from February 15, 1930 to January 29, 1932.

After reaching a balmy 2.6°C on January 10, Winnipeggers did not see above freezing temperatures until March 28. This 76-day streak without reaching the freezing mark was the 20th longest since 1872. Longest was a 108-day streak from November 9, 1996 to February 24, 1997. A list of the longest streaks can be seen here.

The snow was the biggest story of the winter. From November to March, only February saw below normal snowfall. March saw more than double the normal snowfall with 36.4 cm, 22nd snowiest. Both January 2013 and November 2012 were 20th snowiest. By the end of January, Winnipeg had already received an entire year's worth of snowfall (since October). By the end of March, 160.2 cm had fallen since October 1, the 13th snowiest Oct 1 to Mar 31 period since 1872. A list of snowiest Oct 1 to Mar 31 periods can be seen here.

The high snowfall totals created one of the deepest snow packs in years across southern Manitoba. A depth of 58 cm in Winnipeg on March 18 was the deepest snow pack since the great blizzard of April 1997. Snowbanks were massive, making it difficult to move around.

#9 - Mid-summer blues

Early August, persistent northwest flow. CLICK to enlarge

After a hot start to July, summer appeared to be over by the second half of the month. An extended period of fall-like conditions settled in at a time when we are typically at our hottest. This was thanks to the jet stream which featured a deep trough in northern Ontario and a large ridge in western Canada. This maintained a chilly and consistent north/northwest flow over Manitoba which lasted for almost a full month.

27 consecutive days saw below normal temperatures from July 19 to August 14. In this period, highs averaged 22.3°C and lows 8.7°C, both some 4 degrees below normal for the period. The maximum temperature was a measly 25.2°C, startling when you consider the fact that normal highs in the period are 25 to 27°C. 4 days didn't even reach 20°C, while a total of 20 days saw morning lows in the single digits. Many nights saw lows flirting with record lows. On many occasions it got down to between 2 and 5°C across southern Manitoba, 7-10°C below normal.

Winnipeg reached a record low on July 27, dipping to 5.6°C. That broke the old record of 5.8°C in 1978. A full list of records broken on this day can be seen here.

#8 - Twin May rainstorms

Two major Colorado Lows in the second half of May dumped excessive amounts of rainfall in the Red River Valley.

The first system was, of course, during the May long weekend. Showers
and ongoing cloud cover lasted for 5 days from Friday the 17th to
Tuesday the 21st. The heaviest of the rains fell on the 19th and 20th.
Consistent and strong east/northeast winds caused significant upsloping
along the escarpment producing magnificent rain totals in the
southwestern RRV. Locally 100-200 mm of rain fell west and northwest of
Morden, while 50-100 mm fell elsewhere in the southwestern RRV including
over 90 mm in Morden.
Overland flooding and overflowing streams were a major concern.
Basement flooding, road closures and flooded farm fields were some of
the unfortunate consequences. Overland flooding onto the highway forced
the closure of the US border at Gretna. South of the border, 200+ mm of
rain near Walhalla, ND caused the evacuation of Cavalier, ND due to a
potential failure of the dam to the west. Thankfully, the dam did not
fail in the end.

Winnipeg was spared the worst
with ''just'' 15-50 mm of rain. Southern sections saw 30-50 mm while
northern and central parts saw 15-30 mm. Winds were the main concern, with gusts up to 80 km/h on the 20th.

May 30 model forecast showing moisture streaming north

Another slow-moving Colorado Low on May 30-31 brought a repeat performance. Once again, consistent and strong east/northeast winds of 30-40 km/h gusting to 50-60 km/h created significant upsloping along the escarpment.
In just 2 days, 70-120 mm of rain fell in the southwestern and western
RRV including 75 mm in Morden. Overland flooding and bursting streams
were once again a concern. About a dozen highways across southern
Manitoba closed due to washouts, flooding or poor driving conditions due
to mud. A creek that flows through Morden burst its banks and flooded neighbourhoods for the second time. In Winnipeg, a general 35-50 mm of rain fell.
Traffic lights at some intersections were knocked out creating traffic
issues.

Monday, 23 December 2013

Snow and blowing snow is still expected across southern Manitoba overnight tonight and tomorrow morning. A general 1-5 cm can be expected. Strong south winds will create dangerous highway conditions tomorrow morning. However, winds will lighten up in the afternoon and snow will have tapered off. As a result, if you must travel tomorrow, the later you do the better!

The system will usher in some warmer air, but it will only warm to near normal in the high minus teens. This can be partly blamed on the southerly component of the wind funnelling up the valley, not very conducive to drastic warmups, especially this time of year.

Colder air will be ushered in behind the system for Christmas Wednesday with temperatures hovering near or just above -20°C. Some flurries will be possible, especially in the morning.

Seasonably chilly conditions will be the story late week, before our next chance for snow late Friday into Saturday associated with a stronger clipper system. It is too early to call for specific amounts, but 5-10 cm in some areas is possible. It is too early to say if Winnipeg will get into these amounts. Keep in touch with Rob's Blog and A Weather Moment for updates on the system as I will taking a break this week.

At this point, a strong push of very cold air is expected behind that system with a return to very frigid conditions next week.

Sunday, 22 December 2013

Before I get to the snowfall I'd like to mention about temperatures tonight. It is likely that we'll dip below -30°C tonight, and it is possible that we may get as low as the mid -30's if conditions set up good enough. The best chance for lows in the mid to low -30's will be in the Interlake and southwestern Manitoba. The coldest spots could see lows dip as low as -35 to -38°C. Will be interesting to see how cold we get.
Temperatures will rise ahead of a system tomorrow night as winds veer to become southerly.

There's bad news for travellers however for Christmas Eve Tuesday. A system to our north will provide the opportunity for snow and blowing snow. The snow may be heavy at times, especially under any local heavier bands that develop. A general 3-7 cm is expected south of the lakes, with locally higher totals of 10 cm not out of the question under any heavier bands that form. In the Winnipeg area, the snow is expected to begin in the early morning and end in the afternoon.

However, the big story on the highways will be wind. Strong southerly winds will create dangerous highway conditions due to blowing snow. If possible, consider travelling on Monday instead of Tuesday. Will provide another update tomorrow in case things change a bit.

Another push of frigid air moves in behind the system for Christmas day, however it is not expected to last very long with some milder air expected late week.